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The 1,287 genes targeted by the shRNA of the leukemia library.

Standard hematologic parameters in SIRT5-/- mice and SIRT5+/+ littermates.

Plasmids.

Patient sample information.

Antibodies.

We discovered that the survival and growth of many primary acute myeloid leukemia (AML) samples and cell lines, but not normal CD34+ cells, are dependent on SIRT5, a lysine deacylase implicated in regulating multiple metabolic pathways. Dependence on SIRT5 is genotype agnostic and extends to RAS- and p53-mutated AML. Results were comparable between SIRT5 knockdown and SIRT5 inhibition using NRD167, a potent and selective SIRT5 inhibitor. Apoptosis induced by SIRT5 disruption is preceded by reductions in oxidative phosphorylation and glutamine utilization, and an increase in mitochondrial superoxide that is attenuated by ectopic superoxide dismutase 2. These data indicate that SIRT5 controls and coordinates several key metabolic pathways in AML and implicate SIRT5 as a vulnerability in AML.Significance:Reducing SIRT5 activity is detrimental to the survival of AML cells regardless of genotype, yet well tolerated by healthy hematopoietic cells. In mouse models, disrupting SIRT5 inhibits AML progression. SIRT5 controls several metabolic pathways that are required for leukemia cell survival. These results identify SIRT5 as a therapeutic target in AML.See related commentary by Li and Melnick, p. 198.

All supplemental figures and legends.

Next generation sequencing for 52 myeloid malignancies-related genes.

Oligonucleotide sequences.

Ranked list of 1,287 genes from shRNA library screen in primary AML cells. The 1,287 genes assessed with an shRNA library screen were sorted by the second highest percentile fold change present in 2 shRNA and across 2 samples, with the 34 genes showing a fold change in the top 2 percent in more than 2 samples listed first.

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Supplementary Methods, Legends

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Supplementary Figure 2

Purpose:Myelofibrosis is a hematopoietic stem cell neoplasm characterized by bone marrow reticulin fibrosis, extramedullary hematopoiesis, and frequent transformation to acute myeloid leukemia. Constitutive activation of JAK/STAT signaling through mutations in JAK2, CALR, or MPL is central to myelofibrosis pathogenesis. JAK inhibitors such as ruxolitinib reduce symptoms and improve quality of life, but are not curative and do not prevent leukemic transformation, defining a need to identify better therapeutic targets in myelofibrosis.Experimental Design:A short hairpin RNA library screening was performed on JAK2V617F-mutant HEL cells. Nuclear–cytoplasmic transport (NCT) genes including RAN and RANBP2 were among top candidates. JAK2V617F-mutant cell lines, human primary myelofibrosis CD34+ cells, and a retroviral JAK2V617F-driven myeloproliferative neoplasms mouse model were used to determine the effects of inhibiting NCT with selective inhibitors of nuclear export compounds KPT-330 (selinexor) or KPT-8602 (eltanexor).Results:JAK2V617F-mutant HEL, SET-2, and HEL cells resistant to JAK inhibition are exquisitely sensitive to RAN knockdown or pharmacologic inhibition by KPT-330 or KPT-8602. Inhibition of NCT selectively decreased viable cells and colony formation by myelofibrosis compared with cord blood CD34+ cells and enhanced ruxolitinib-mediated growth inhibition and apoptosis, both in newly diagnosed and ruxolitinib-exposed myelofibrosis cells. Inhibition of NCT in myelofibrosis CD34+ cells led to nuclear accumulation of p53. KPT-330 in combination with ruxolitinib-normalized white blood cells, hematocrit, spleen size, and architecture, and selectively reduced JAK2V617F-mutant cells in vivo.Conclusions:Our data implicate NCT as a potential therapeutic target in myelofibrosis and provide a rationale for clinical evaluation in ruxolitinib-exposed patients with myelofibrosis.

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ImportanceMinoritized groups are less likely to receive COVID-19 therapeutics, but few studies have identified potential methods to reduce disparities.ObjectiveTo determine whether screening plus outreach, when compared with referral alone, increases identification of vulnerable pediatric patients at high risk for severe disease eligible for COVID-19 therapeutics from low-resourced communities.Design, Setting, and ParticipantsA retrospective cohort study of COVID-19 medication allocation between January 1, 2022, and February 15, 2022, at Lurie Children’s Hospital, a quaternary care children’s hospital, in Chicago, Illinois. The cohorts were pediatric patients referred for COVID-19 therapeutics or with a positive SARS-CoV-2 polymerase chain reaction within the hospital system followed by outreach. Screening involved daily review of positive cases of SARS-CoV-2, followed by medical record review for high-risk conditions, and communication with clinicians and/or patients and families to offer therapy.ExposuresDiagnosis of COVID-19.Main Outcomes and MeasuresThe primary measure was difference in child opportunity index (COI) scores between the 2 cohorts. Secondary measures included presence and duration of symptoms at diagnosis, medication uptake, race and ethnicity, insurance type, qualifying medical condition, sex, primary language, and age.ResultsOf 145 total patients, the median (IQR) age was 15 (13-17) years, and most were male (87 participants [60.0%]), enrolled in public insurance (83 participants [57.2%]), and members of minoritized racial and ethnic groups (103 participants [71.0%]). The most common qualifying conditions were asthma and/or obesity (71 participants [49.0%]). From 9869 SARS-CoV-2 tests performed, 94 eligible patients were identified via screening for COVID-19 therapeutics. Fifty-one patients were identified via referral. Thirty-two patients received medication, of whom 8 (25%) were identified by screening plus outreach alone. Compared with referred patients, patients in the screening plus outreach group were more likely to have moderate, low, or very low COI composite scores (70 patients [74.5%] vs 27 patients [52.9%]); public insurance (65 patients [69.1%] vs 18 patients [35.3%]); and asthma or obesity (60 patients [63.8%] vs 11 patients [21.6%]). Patients in the referral group were more likely to be non-Hispanic White (23 patients [45.1%] vs 19 patients [20.2%]) and receive medication (24 patients [47.1%] vs 8 patients [8.5%]).Conclusions and RelevanceCompared with referral patients, screening plus outreach patients for COVID-19 medications were more socially vulnerable, with lower COI scores, and more likely to have asthma or obesity. Future studies should investigate communication strategies to improve uptake of these medications after outreach.

Background Streptococcus pyogenes (GAS) is the major cause of bacterial pharyngitis in children. GAS can cause conditions ranging from asymptomatic pharyngeal carriage to invasive infection. We compared the genomic characteristics of GAS pharyngeal and invasive isolates from U.S. children. Methods We cultured GAS from throat swabs collected from children aged 3–18 years with acute GAS pharyngitis, diagnosed by rapid antigen or molecular test, and from a convenience sample of asymptomatic children during 1/2020 to 3/2022 in Chicago, IL; Atlanta, GA; Portland, OR; Phoenix, AZ. We collected invasive isolates in Chicago. Whole-genome sequencing (WGS) was performed on the Illumina MiSeq for species confirmation, isolate typing, and virulence and antimicrobial gene identification. Reference-based read alignment was used for whole genome phylogenetic analysis. Results Of 1144 collected throat swabs, 684 were from children with pharyngitis and 460 from asymptomatic children. 13 invasive GAS isolates were collected. GAS were cultured from 359 pharyngitis and 20 asymptomatic swabs. Of these, 371 GAS isolates could be recovered and underwent WGS. Thirty isolates (8%) were either low-quality sequences and/or identified as species other than S. pyogenes and were excluded. Whole-genome phylogenetic analysis of 341 GAS (215 pharyngitis, 13 asymptomatic, 13 invasive) identified 25 related clusters and 8 singletons (Figure 1). Virulence gene complements within given emm types were generally concordant with recently published CDC strain data. The most frequently identified resistance genes were tetM and ermB. 281 isolates (82%) carried no antibiotic resistance genes. Some clusters were significantly more represented at certain sites within apparent geographically defined clusters of nearly indistinguishable isolates (Figure 1): cluster 1 in Chicago, emm type 3; cluster 14 in Phoenix and Portland, emm 28, 12; and cluster 15 in Atlanta, emm 89. No major genomic factors were significantly associated with asymptomatic vs pharyngitis vs invasive presentation. Figure 1:Whole genome phylogenetic tree of pediatric GAS isolates Maximum likelihood phylogenetic analysis based on whole-genome alignment of 371 Group A Streptococcus isolates. Tip colors represent cluster assignments based on genetic similarity. Inner ring represents geographic location of GAS isolation. Outer ring represents patient presentation: asymptomatic colonization, symptomatic pharyngitis, or invasive infection. Conclusion Pharyngeal and invasive GAS in children within individual clonal complexes are co-included in closely related clusters, with evidence of close transmission within individual sites Disclosures All Authors: No reported disclosures.

Background COVID-19 affected the epidemiology of many respiratory pathogens including GAS. Assessing genetic heterogeneity (emm type, antimicrobial resistance, virulence factors) can inform treatment recommendations and targets for potential GAS vaccines. We assessed GAS clinical antibiotic susceptibility and performed whole genome sequencing (WGS) among pediatric pharyngeal isolates from 2020–2022. Methods From 1/2020–3/2022 we collected throat swabs in pediatric clinics and EDs from children aged 3-18 years in Chicago, IL; Atlanta, GA; Portland, OR; and Phoenix, AZ: 1) with acute GAS pharyngitis and 2) among a convenience sample of asymptomatic children to assess for GAS colonization. Swabs were plated on blood agar. E-tests were used to assess clinical susceptibility to erythromycin (ERY) and ciprofloxacin (CIP). emm type and antimicrobial resistance genes (ERY, Clindamycin (CLI), and fluoroquinolones) were assessed by WGS. Results 1144 pharyngeal swabs were collected: 359/684 (52%) from children with GAS pharyngitis by rapid test and 20/460 (4.3%) from asymptomatic children yielded GAS on culture. Phenotypic resistance: 55/364 (15%) tested isolates were ERY resistant and 5/364 (1.4%) CIP resistant. The proportion of isolates with ERY resistance increased significantly from 2020 (6%) to 2021–2022 (25%) (χ2 = 23.70, p< .00001) (Figure 1). MICs were high among ERY resistant GAS (Table 1). Genotypic resistance: Of 304 sequenced GAS isolates 40/304 (13%) were ERY resistant, 35/304 (11.5%) were both ERY resistant and CLI (inducible or constitutive) resistant, and 4/304 (1.3%) fluoroquinolone resistant. ermB (62%) was the most common gene for ERY resistance and constitutive CLI resistance, followed by ermTR (23%) and ermT (11%) both conferring inducible CLI resistance. Among the 20 isolates from asymptomatic children no ERY, CLI, or CIP resistance occurred, and no resistance genes were identified. emm types 11, 9, 77, 58 and 94 were associated with ERY and CLI resistance. Conclusion ERY resistance increased from 2020–2022. The high rate of CLI resistance among ERY resistant GAS was associated with erm genes. These results are important to inform treatment recommendations for GAS pharyngitis and targets for vaccine development that can reduce antimicrobial-resistant GAS disease. Disclosures All Authors: No reported disclosures.

Background The COVID-19 pandemic has affected respiratory disease epidemiology. Measures to reduce transmission of SARS-CoV-2 (e.g., masking, social distancing, school closures) have reduced the incidence of common infectious diseases. At least one early report described changes in rates of pediatric GAS pharyngitis. We sought to determine the difference in GAS pharyngitis rates before and after the onset of the pandemic at our children’s hospital. Methods Clinical pharyngeal specimens tested for GAS by rapid antigen tests (RADTs) or LAMP methodology (loop-mediated isothermal amplification of GAS DNA) from January 2019 to March 2022 at our children’s hospital were analyzed. Clinician’s evaluating patients for GAS pharyngitis perform a RADT, when positive the patient is treated for GAS pharyngitis. When the RADT is negative, a LAMP test is performed. Patients were considered test-positive if either test was positive regardless of clinical symptoms. Annual positivity rates were compared using statistical process control (SPC) charts with both 2019 and 2020 as baseline years (i.e., 2019 vs 2020-3/2022; 2020 vs 2021-3/2022). The change in GAS incidence rate (positive patients/1000 tested) between years was assessed by chi-square tests. Results 9,896 patients had throat swabs tested for GAS from January 2019 through March 2022. Using SPC with 2019 as a baseline, there was a 15.1% decrease in mean GAS positivity through 3/2022. With 2020 as baseline, there was a 13.0% decrease in mean GAS positivity through 3/2022. The incidence of positive GAS tests decreased significantly: 2019 vs. 2020-3/2022 (x2 = 84.97, p ≤0.00001) and 2020 vs. 2021-3/2022 (x2 = 154.01, p ≤0.00001). Figure 1. Conclusion Using throat swab results, the incidence of pediatric GAS pharyngitis at our hospital has decreased significantly during the COVID-19 pandemic. Implications: Pandemic-related risk mitigation measures, such as masking, social distancing, and school closures, were associated with significantly decreased incidence of GAS pharyngitis. It is likely that GAS colonization and invasive infections were also affected. Disclosures All Authors: No reported disclosures.

Multisystem Inflammatory Syndrome in Children (MIS-C) often involves a post-viral myocarditis and associated left ventricular dysfunction. We aimed to assess myocardial function by strain echocardiography after hospital discharge and to identify risk factors for subacute myocardial dysfunction. We conducted a retrospective single-center study of MIS-C patients admitted between 03/2020 and 03/2021. Global longitudinal strain (GLS), 4-chamber longitudinal strain (4C-LS), mid-ventricular circumferential strain (CS), and left atrial strain (LAS) were measured on echocardiograms performed 3-10 weeks after discharge and compared with controls. Among 60 MIS-C patients, hypotension (65%), ICU admission (57%), and vasopressor support (45%) were common, with no mortality. LVEF was abnormal ( 55%) in 29% during hospitalization but only 4% at follow-up. Follow-up strain abnormalities were prevalent (GLS abnormal in 13%, 4C-LS in 18%, CS in 16%, LAS in 5%). Hypotension, ICU admission, ICU and hospital length of stay, and any LVEF 55% during hospitalization were factors associated with lower strain at follow-up. Higher peak C-reactive protein (CRP) was associated with hypotension, ICU admission, total ICU days, and with lower follow-up GLS (r = - 0.55; p = 0.01) and CS (r = 0.41; p = 0.02). Peak CRP 18 mg/dL had negative predictive values of 100% and 88% for normal follow-up GLS and CS, respectively. A subset of MIS-C patients demonstrate subclinical systolic and diastolic function abnormalities at subacute follow-up. Peak CRP during hospitalization may be a useful marker for outpatient cardiac risk stratification. MIS-C patients with hypotension, ICU admission, any LVEF 55% during hospitalization, or a peak CRP 18 mg/dL may warrant closer monitoring than those without these risk factors.

We discovered that the survival and growth of many primary acute myeloid leukemia (AML) samples and cell lines, but not normal CD34+ cells, are dependent on SIRT5, a lysine deacylase implicated in regulating multiple metabolic pathways. Dependence on SIRT5 is genotype agnostic and extends to RAS- and p53-mutated AML. Results were comparable between SIRT5 knockdown and SIRT5 inhibition using NRD167, a potent and selective SIRT5 inhibitor. Apoptosis induced by SIRT5 disruption is preceded by reductions in oxidative phosphorylation and glutamine utilization, and an increase in mitochondrial superoxide that is attenuated by ectopic superoxide dismutase 2. These data indicate that SIRT5 controls and coordinates several key metabolic pathways in AML and implicate SIRT5 as a vulnerability in AML. Significance: Reducing SIRT5 activity is detrimental to the survival of AML cells regardless of genotype, yet well tolerated by healthy hematopoietic cells. In mouse models, disrupting SIRT5 inhibits AML progression. SIRT5 controls several metabolic pathways that are required for leukemia cell survival. These results identify SIRT5 as a therapeutic target in AML. See related commentary by Li and Melnick, p. 198.

Introduction: Multisystem Inflammatory Syndrome in Children (MIS-C) associated with COVID-19 can cause cardiovascular dysfunction. We aimed to determine if strain abnormalities persist in MIS-C patients 3-10 weeks post-discharge, and whether acute markers of clinical severity are associated with lower strain at subacute follow-up. Methods: We performed a retrospective cohort study of MIS-C patients admitted at a single center from 3/2020-3/2021. Demographic and clinical variables during hospitalization were obtained. Global longitudinal strain (GLS), 4-chamber longitudinal strain (4C-LS), mid-papillary circumferential strain (CS), and left atrial strain (LAS) at 3-10 week follow-up were compared to age matched controls (n=10). Bivariate analyses were performed using Spearman rank correlation and two-sample t-test or Wilcoxon rank sum test. Results: Sixty MIS-C patients were identified (age 8.9 +/- 4 years, 35/60 male, 39% Hispanic, 29% African American). Hypotension (65%), ICU admission (57%), and inotropic support (45%) were common; 7% received mechanical ventilation. No deaths or need for ECMO were reported. Median length of stay (LOS) was 7 days. LVEF was Conclusions: MIS-C patients show abnormal strain during subacute follow-up despite improvement in EF. Lower CS, GLS, and 4C-LS were associated with in-hospital markers of clinical severity. This data may allow for identification of at-risk MIS-C patients and help guide outpatient cardiology follow-up.

Objective:To identify the impact of universal masking on COVID-19 incidence and putative SARS-CoV-2 transmissions events among children’s hospital healthcare workers (HCWs).Design:Quasi-experimental study.Setting:Single academic free-standing children’s hospital.Methods:We performed whole-genome sequencing of SARS-CoV-2- PCR-positive samples collected from HCWs 3 weeks before and 6 weeks after implementing a universal masking policy. Phylogenetic analyses were performed to identify clusters of clonally related SARS-CoV-2 indicative of putative transmission events. We measured COVID-19 incidence, SARS-CoV-2 test positivity rates, and frequency of putative transmission events before and after the masking policy was implemented.Results:HCW COVID-19 incidence and test positivity declined from 14.3 to 4.3 cases per week, and from 18.4% to 9.0%, respectively. Putative transmission events were only identified prior to universal masking.Conclusions:A universal masking policy was associated with reductions in HCW COVID-19 infections and occupational acquisition of SARS-CoV-2.

Background Cardiac evaluations, including cardiovascular magnetic resonance (CMR) imaging and biomarker results, are needed in children during mid-term recovery after infection with SARS-CoV-2. The incidence of CMR abnormalities 1–3 months after recovery is over 50% in older adults and has ranged between 1 and 15% in college athletes. Abnormal cardiac biomarkers are common in adults, even during recovery. Methods We performed CMR imaging in a prospectively-recruited pediatric cohort recovered from COVID-19 and multisystem inflammatory syndrome in children (MIS-C). We obtained CMR data and serum biomarkers. We compared these results to age-matched control patients, imaged prior to the SARS-CoV-2 pandemic. Results CMR was performed in 17 children (13.9 years, all ≤ 18 years) and 29 age-matched control patients without SARS-CoV-2 infection. Cases were recruited with symptomatic COVID-19 (11/17, 65%) or MIS-C (6/17, 35%) and studied an average of 2 months after diagnosis. All COVID-19 patients had been symptomatic with fever (73%), vomiting/diarrhea (64%), or breathing difficulty (55%) during infection. Left ventricular and right ventricular ejection fractions were indistinguishable between cases and controls (p = 0.66 and 0.70, respectively). Mean native global T1, global T2 values and segmental T2 maximum values were also not statistically different from control patients (p ≥ 0.06 for each). NT-proBNP and troponin levels were normal in all children. Conclusions Children prospectively recruited following SARS-CoV-2 infection had normal CMR and cardiac biomarker evaluations during mid-term recovery. Trial Registration Not applicable.

Purpose: Myelofibrosis is a hematopoietic stem cell neoplasm characterized by bone marrow reticulin fibrosis, extramedullary hematopoiesis, and frequent transformation to acute myeloid leukemia. Constitutive activation of JAK/STAT signaling through mutations in JAK2, CALR, or MPL is central to myelofibrosis pathogenesis. JAK inhibitors such as ruxolitinib reduce symptoms and improve quality of life, but are not curative and do not prevent leukemic transformation, defining a need to identify better therapeutic targets in myelofibrosis. Experimental Design: A short hairpin RNA library screening was performed on JAK2V617F-mutant HEL cells. Nuclear–cytoplasmic transport (NCT) genes including RAN and RANBP2 were among top candidates. JAK2V617F-mutant cell lines, human primary myelofibrosis CD34+ cells, and a retroviral JAK2V617F-driven myeloproliferative neoplasms mouse model were used to determine the effects of inhibiting NCT with selective inhibitors of nuclear export compounds KPT-330 (selinexor) or KPT-8602 (eltanexor). Results: JAK2V617F-mutant HEL, SET-2, and HEL cells resistant to JAK inhibition are exquisitely sensitive to RAN knockdown or pharmacologic inhibition by KPT-330 or KPT-8602. Inhibition of NCT selectively decreased viable cells and colony formation by myelofibrosis compared with cord blood CD34+ cells and enhanced ruxolitinib-mediated growth inhibition and apoptosis, both in newly diagnosed and ruxolitinib-exposed myelofibrosis cells. Inhibition of NCT in myelofibrosis CD34+ cells led to nuclear accumulation of p53. KPT-330 in combination with ruxolitinib-normalized white blood cells, hematocrit, spleen size, and architecture, and selectively reduced JAK2V617F-mutant cells in vivo. Conclusions: Our data implicate NCT as a potential therapeutic target in myelofibrosis and provide a rationale for clinical evaluation in ruxolitinib-exposed patients with myelofibrosis.

Background Antimicrobial impregnated catheters (AIC) are one strategy to prevent CLABSI with existing data for central lines required for short duration, however, the strength of evidence, particularly for children, is lacking. Recent 3-year CLABSI data at our institution show 60 (51%) infections occurred in central lines within 8 weeks of insertion, suggesting an opportunity for evaluation of an intervention targeting this time frame. We implemented AIC to evaluate their effectiveness in reducing CLABSI standardized infection ratio (SIR) in patients requiring central venous access for less than 8 weeks. We also monitored for complications (malfunction, line exchange, fungal infection). Methods A stepped wedge observational design was used to implement Minocycline + Rifampin impregnated catheters in a rolling fashion across the institution. Children > 3kg were eligible if admitted to a participating unit and required central venous access through a peripherally inserted central catheter (PICC), non-tunneled catheter, or tunneled non-cuffed femoral catheter for < 8 weeks. Units, prioritized based on CLABSI SIR, were added to the intervention monthly until AIC were used throughout the institution. A multidisciplinary team (infectious diseases and infection control experts, CLABSI leaders, unit-based physicians and nurses, proceduralists, supply chain) met weekly to facilitate implementation, assess for CLABSI and monitor for complications. Figure 1. Study design. This figure describes the stepped wedge study design where units were phased into the invention on a rolling monthly basis allowing for comparison between and within units. The shaded boxes represent time periods when units were using antimicrobial impregnated catheters and the white boxes represent time periods when units were using standard non-impregnated catheters. Results AIC were systematically implemented over a 7-month period. The institution’s CLABSI SIR decreased from 0.80 to 0.59 during this timeframe. There were no NHSH defined CLABSI in patients with an AIC during the intervention. Obstacles included shortage of catheters due to supply chain disruption, adjustment of technique for line insertion and cracked/broken lines. Infections and complications were reviewed by the multidisciplinary team and compared to historical rates with non-impregnated lines. This figure shows the institution’s rolling 12-month SIR during the intervention period. Conclusion CLABSI SIR decreased at our institution during the intervention period. While many efforts likely led to this reduction (optimizing maintenance bundle, unit based CLABSI initiatives), we believe the use of AIC contributed to this improvement. There were no pediatric-specific safety events identified during implementation. Disclosures Ravi Jhaveri, MD, AstraZeneca (Consultant)Dynavax (Consultant)Elsevier (Other Financial or Material Support, Editorial stipend as Co-EiC, Clinical Therapeutics)Hologic (Consultant)Seqirus (Consultant)

Dubois et al. report results of a meta-analysis assessing the diagnostic accuracy of rapid nucleic acid tests (RNATs) for group A Streptococcus (GAS) pharyngitis. While the accuracy of any diagnostic assay is crucial, the clinical application of these tests must be considered as these molecular assays become more widely implemented. We provide commentary to highlight the considerations for optimal use of RNATs in practice, taking into account the appropriate clinical context and setting to perform and evaluate these tests. Specifically, we address the critical clinical questions: “What is the benefit of rapid testing for GAS?” and “Under what circumstances should RNATs for GAS be utilized?”

Background: Postoperative infections can occur during surgical replacement of pulse generators for pacemakers and implantable cardioverter-defibrillators. The incidence of infection is poorly documented in children and patients with adult congenital heart disease. The utility of surveillance cultures obtained from device pocket swabs is unknown in this group. Methods: We reviewed surgical replacements of cardiovascular implantable pulse generators from 2010 to 2017. Two cohorts were defined. In a surveillance cohort (123 patients), aerobic and anaerobic culture swabs of the device pocket were obtained at the time of generator change. In a nonsurveillance cohort (107 patients), generator change occurred without obtaining cultures. Results: During 230 generator changes (mean patient age 19 years; 77% with structural congenital heart disease), two clinical infections occurred at the surgical site (0.9% incidence). Neither infection occurred in the surveillance cohort. Cultures were positive in 12 (9.8%) of 123 patients in the surveillance cohort, but 11 of 12 were likely contaminants and none were subsequently associated with clinical disease. There was no association between clinical infection or positive surveillance cultures and the location of pulse generator, the presence of other concurrent surgeries, or a history of prior pocket infection. Conclusions: Clinical infection was rare after pulse generator change in children and young adults. No cases required reintervention on the pocket. Surveillance cultures did not improve clinical care. These data extend current recommendations that surveillance cultures are not required during generator change to the pediatric and young adult population.

Context: Chronic myelomonocytic leukemia (CMML) is a rare hematopoietic stem cell disorder that predominantly affects the elderly. Previous genetic analysis supports the presence of mutations including ASXL1, TET2, spliceosome components (SF3B1, SRSF2, U2AF1, and ZRSR2), and the oncogenic RAS pathway (NRAS, KRAS, CBL, PTPN11, and NF1). Objective: As part of a precision cancer surveillance to increase our basic, translational, and clinical understanding of rare diseases at the Huntsman Cancer Institute, we identified a cohort of patients with CMML treated at our institution. This report reports their clinical and molecular characteristics based on standard of care molecular profiling with myeloid next-generation sequencing. We also describe the overall survival of patients with molecular profiles of interest. Design: We extracted data from 57 CMML patients from the Huntsman Cancer Institute electronic health record system. We categorized the patients using their first bone marrow myeloid malignancy panel diagnosis between October 2009 and September 2020. We reviewed their charts for the following information elements: date of birth, sex, vital status, bone marrow biopsy, CMML diagnosis, and date of death or last follow-up. Our analysis was performed by producing Kaplan-Meier survival curves. Results: We identified a total of 34 gene mutationstal Saint-Louis, Paris, France

FLT3-ITD mutations occur in 20-30% of AML patients and are associated with aggressive disease. Patients with relapsed FLT3-mutated disease respond well to 2nd generation FLT3 TKIs but inevitably relapse within a short timeframe. In this setting, until overt relapse occurs, the bone marrow microenvironment facilitates leukemia cell survival despite continued on-target inhibition. We demonstrate that human bone marrow derived conditioned medium (CM) protects FLT3-ITD+ AML cells from the 2nd generation FLT3 TKI quizartinib and activates STAT3 and STAT5 in leukemia cells. Extrinsic activation of STAT5 by CM is the primary mediator of leukemia cell resistance to FLT3 inhibition. Combination treatment with quizartinib and dasatinib abolishes STAT5 activation and significantly reduces the IC50 of quizartinib in FLT3-ITD+ AML cells cultured in CM. We demonstrate that CM protects FLT3-ITD+ AML cells from the inhibitory effects of quizartinib on glycolysis and that this is partially reversed by treating cells with the combination of quizartinib and dasatinib. Using a doxycycline-inducible STAT5 knockdown in the FLT3-ITD+ MOLM-13 cell line, we show that dasatinib-mediated suppression of leukemia cell glycolytic activity is STAT5-independent and provide a preclinical rationale for combination treatment with quizartinib and dasatinib in FLT3-ITD+ AML.

Nutritional supplements for patients with exocrine pancreatic insufficiency (EPI) typically utilize pancreatic enzyme replacement therapy (PERT) which is associated with gastrointestinal side effects. We evaluated serum triglyceride levels in patients with cystic fibrosis following consumption of an enzyme-modified oil oral nutritional supplement (EMO-ONS) versus a standard triacylglycerol-based ONS product (TAG-ONS) used concomitantly with PERT and patient tolerability between the two approaches. Ten subjects with CF and EPI taking PERT were enrolled in a single-center, double-blind, cross-over proof of concept trial. Five subjects randomized to Arm 1 were administered a PERT placebo and EMO-ONS and 5 subjects in Arm 2 were administered TAG-ONS+PERT. After 4 to 14 days, subjects received the opposite ONS. Serum triglyceride levels were measured at baseline and hourly for 6 h. Following the above, subjects were randomly assigned to receive 2 daily servings of EMO-ONS+PERT placebo or TAG-ONS+PERT at home for 7-days, self-reporting gastrointestinal symptoms daily. Mean change in peak serum triglyceride levels were similar for both groups (EMO-ONS = 41.9 ± 46.7 mg/dL vs. TAG-ONS+PERT = 46.4 ± 44.1 mg/L; p = 0.85). There was no difference in mean ratio of the serum triglyceride AUC between the two groups (p = 0.58) or self-reported gastrointestinal tolerance. EMO-based products may provide a PERT-free alternative to traditional ONS products in patients with cystic fibrosis.

Inhaled levodopa is a newly emerging therapeutic option in the treatment of "off " symptoms associated with Parkinson's disease (PD). Its mode of delivery offers more rapid absorption of levodopa and shorter onset of clinical benefit compared to oral formulations, and has been shown to be feasible for use in patients with PD experiencing worse motor function due to declining plasma levodopa levels. Clinical development of this compound is supported by preclinical, Phase I-III, long-term-safety studies and studies in special populations, including otherwise-healthy asthmatics and smokers. These investigations demonstrated that the drug is well tolerated without risk of long-term (up to 1 year) changes in pulmonary function or spirometry measures. The most common side effects among PD patients were a mild cough, upper respiratory tract infection, nausea, sputum discoloration, and dyskinesia. Inhaled levodopa offers a different administration method and side-effect profile from the currently available options for rescue therapy for Off periods in PD, though comparative studies have not been performed. The drug is presently under review by the US Food and Drug Administration.

// Ami B. Patel 1, * , Thoralf Lange 5, * , Anthony D. Pomicter 2, * , Christopher J. Conley 2 , Christina A. Harrington 4 , Kimberly R. Reynolds 2 , Todd W. Kelley 3 , Thomas O’Hare 1, 2 and Michael W. Deininger 1, 2 1 Division of Hematology and Hematologic Malignancies, The University of Utah, Salt Lake City, UT, USA 2 Huntsman Cancer Institute, The University of Utah, Salt Lake City, UT, USA 3 Department of Pathology, The University of Utah, Salt Lake City, UT, USA 4 Integrated Genomics Laboratory, Oregon Health and Science University, Portland, OR, USA 5 University of Leipzig, Division of Haematology and Oncology, Leipzig, Germany * These authors contributed equally to this work Correspondence to: Michael W. Deininger, email: Michael.Deininger@hci.utah.edu Keywords: chronic myeloid leukemia; BCR-ABL1; deep molecular response; treatment-free remission Received: January 20, 2018 Accepted: March 15, 2018 Published: April 03, 2018 ABSTRACT The life expectancy of patients with chronic phase chronic myeloid leukemia on tyrosine kinase inhibitor therapy now approaches that of the general population. Approximately 60% of patients treated with second generation tyrosine kinase inhibitors achieve a deep molecular response, the prerequisite for a trial of treatment-free remission. Those patients unlikely to achieve deep molecular response may benefit from more intensive therapy up front. To identify biomarkers predicting deep molecular response we performed transcriptional profiling on CD34 + progenitor cells from newly diagnosed chronic phase chronic myeloid leukemia patients treated with nilotinib on a prospective clinical trial. Using unsupervised and targeted analytical strategies, we show that gene expression profiles are similar in patients with and without subsequent deep molecular response. This result is in contrast to the distinct expression signature of CD34 + chronic phase chronic myeloid leukemia patients failing to achieve a cytogenetic response on imatinib and suggests that deep molecular response to second-generation tyrosine kinase inhibitors is governed by the biology of more primitive chronic myeloid leukemia cells or extrinsic factors.

Background: Selinexor is an oral, small molecule, selective inhibitor of nuclear export (SINE) compound that specifically blocks the karyopherin protein exportin 1 (XPO1, CRM1). In an shRNA library screen, we discovered that the survival of JAK2V167F mutant HEL cells is dependent on XPO1-mediated nuclear-cytoplasmic transport. Selinexor selectively suppressed primary myelofibrosis (MF) cells as compared with normal progenitor cells and induced hematologic responses in an MPN mouse model. Methods: An open label, prospective, investigator-initiated single center study is ongoing in adults with primary or secondary MF with resistance or intolerance to JAK inhibitor (JAKi) therapy with platelets > 30 K/μL and neutrophils > 500/μL. Selinexor was given orally once a week. Spleen volume was assessed by MRI at week 12 and week 24. The study was amended to include additional MRIs every 12 weeks in the year 1 and 24 weeks in the year 2. Primary end point is spleen response, defined as ≥ 35% spleen volume reduction (SVR) by MRI or CT, where applicable) at week 24. Bone marrow was evaluated at baseline and at week 24. The projected sample size of 24 will provide 83% power to reject a response rate of 15% and allow for up to a 25% dropout rate. We provide an interim report after completing 50% enrollment. Results: Between May 2019 and February 2021, 12 patients (pts) were enrolled. JAK2, CALR and MPL mutations were present in 7 (58.3%), 4 (33.3%) and 1 (8.3%) pts respectively. Eight pts (66.6%) had at least one high molecular risk mutation at baseline (Table 1). Median duration of prior JAKi therapy was 22 months (0.5 to 96 months) and 11 out of 12 were refractory to ruxolitinib at study enrollment. Median baseline spleen volume was 1454 cm 3(range 835 to 5792). Selinexor starting dose was 80 mg weekly in the first 6 pts and 60 mg for subsequent pts. At data cutoff, median duration of selinexor therapy was 36 weeks (range 11-114 weeks). One pt was not response evaluable and died due to liver abscess at week 12 (unrelated). One pt discontinued selinexor at week 18 due to grade 3 fatigue and was not evaluable for the primary end point. Of the 11 pts who had week 12 MRI or CT, 6 showed ≥ 10% SVR, 3 showed ≥ 25% SVR and 1 pt had early progression (Figure 1). At week 24, 5/9 (56%) pts had ≥ 25% SVR and 2/9 (22%) had ≥ 35% SVR (Figure 1). In 9 pts who had ≥24 weeks of selinexor, SVR ≥ 25% and ≥ 35% occurred at any point during study treatment in 4 (44%) and 3 (33%) pts, respectively. Two pts were red cell transfusion dependent at baseline; 1 became transfusion independent after 36 weeks of treatment, has not required transfusion for 49 weeks and remains on study treatment to date (114 weeks). Six pts (50%) discontinued selinexor. Reasons for treatment discontinuation are death in 1 pt, progressive disease in 1 pt, alternative treatment in 2 pts, and toxicity in 2 pts. Ten pts required dose reduction due to fatigue (1pt), anemia (1 pt), thrombocytopenia (2 pts), abdominal pain (1pt) and weight loss (5 pts). The most common treatment related adverse event was weight loss (grade 2 in 4 pts and grade 3 in 1 pt). This was manageable with treatment interruption and dose reduction, except in one pt who discontinued selinexor. As yet no changes in reticulin fibrosis MF grade were observed among 9 patients who received at least 24 weeks of treatment. Conclusions: Once weekly, oral selinexor showed single agent activity with sustained spleen responses in pts with JAKi refractory MF. Long-term administration of selinexor was well tolerated over time in MF pts. Correlatives studies including circulating inflammatory cytokine levels and mutant allele burden, as well as clonality studies by X-chromosome inactivation studies in woman, are underway and will be presented. Figure 1 Figure 1. Disclosures Tantravahi: BMS: Research Funding; Novartis: Research Funding; CTI BioPharma: Research Funding; Abbvie Inc.: Research Funding; Karyopharm Therapeutics Inc.: Consultancy, Honoraria, Research Funding. Patel: Stemline: Research Funding; Genentech: Research Funding; Roche: Research Funding. Chamoun: Karyopharm Therapeutics Inc.: Current Employment, Current equity holder in publicly-traded company. Shah: Karyopharm: Current Employment. George: Celgene: Consultancy; Bristol Meyers Squibb: Consultancy; Incyte Corporation: Consultancy; Blueprint Medicines: Consultancy. Deininger: Fusion Pharma, Medscape, DisperSol: Consultancy; SPARC, DisperSol, Leukemia & Lymphoma Society: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Part of a Study Management Committee, Research Funding; Blueprint Medicines Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Part of a Study Management Committee, Research Funding; Novartis: Consultancy, Research Funding; Sangamo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Research Funding.